Okay the 22 page pdf makes a lot of sense to me, acutally. Especially how it says a stiff driver is best, not a high excursion one as others thought. the pdf at least has some pictures, though they are grainy, if someone could decipher the instructions and clarifiy them for me I would really like to build this. How much of that pdf is transcribed from stuff G.H. said and how much of it was made up by the South African? I am wary of the different sizes of the pieces given for each driver size. Just seems like the box would be the same to have the same frequency resonance range.
http://www.avforums.com/forums/atta...iman-infrasonic-generator-graham-holliman.pdf
http://www.avforums.com/forums/atta...iman-infrasonic-generator-graham-holliman.pdf
Hello Oliver,
Excellent! Following your instruction I could open the document and I'll study it.
Thanks you a lot for the help!
Best regards from Paris, France
Jean-Michel Le Cléac'h
Excellent! Following your instruction I could open the document and I'll study it.
Thanks you a lot for the help!
Best regards from Paris, France
Jean-Michel Le Cléac'h
Yeah, if you're talking about the imageshack images of the thing that is taller than it is wide and long, that's not the Gragam Holliman.
As far as the driver, I'll bet you that the closest match you'd find to the intended driver would be more like a P.A. or instrument speaker like a Peavy, such as this one:
Peavey 18LOMAX 2400-Watt 18" Subwoofer 18 Low Max#
This is not the Graham Holliman:
http://img78.imageshack.us/img78/659/infrard1.gif
It starts out like the G.H. but then it's just a folded horn. But it is about as complicated and looks just as difficult to build, so why does it seem like no one here has built the G.H. to the dimensions shown on the 22 page pdf? Just because you don't think it's original?
As far as the driver, I'll bet you that the closest match you'd find to the intended driver would be more like a P.A. or instrument speaker like a Peavy, such as this one:
Peavey 18LOMAX 2400-Watt 18" Subwoofer 18 Low Max#
This is not the Graham Holliman:
http://img78.imageshack.us/img78/659/infrard1.gif
It starts out like the G.H. but then it's just a folded horn. But it is about as complicated and looks just as difficult to build, so why does it seem like no one here has built the G.H. to the dimensions shown on the 22 page pdf? Just because you don't think it's original?
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it would be interesting to see a model of it and how the stubs interact with the tuned inner chamber
fwiw I once had a Hegeman/Shahinian "Contrabombarde" subwoofer (which IIRC ran two custom Oaktron 8" woofers) that had impressive reviews - a simple BP4 box with a cheap 12" and 4" pvc front chamber vent. was probably better. There was chuffing in the Contrabombarde. Re: Rob's 18" interpretation = more work and not sure what he was getting at - he said it would set off car alarms when played loud outdoors.
why did the designer pick a 45 degree chamfer for the cavity tuning hole? - I could see rounding the hole.
Was the G-H meant to primarily have its vents facing forwards or could it also set on feet gapping the vents from the floor?
fwiw I once had a Hegeman/Shahinian "Contrabombarde" subwoofer (which IIRC ran two custom Oaktron 8" woofers) that had impressive reviews - a simple BP4 box with a cheap 12" and 4" pvc front chamber vent. was probably better. There was chuffing in the Contrabombarde. Re: Rob's 18" interpretation = more work and not sure what he was getting at - he said it would set off car alarms when played loud outdoors.
why did the designer pick a 45 degree chamfer for the cavity tuning hole? - I could see rounding the hole.
Was the G-H meant to primarily have its vents facing forwards or could it also set on feet gapping the vents from the floor?
An externally hosted image should be here but it was not working when we last tested it.
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Aren't the vents on the bottom on each end? I really want to build one, but I will not shoot into the darkess with half instructions and no good images or renders. The idea of clean, low infra bass is spectacular, and with the intricacy of the design this does not seem to be "too good to be true, so it is." Any of you guys ever auditioned a rotary woofer installation? I can't believe I haven't gone to Niagara Falls where they have six installed as part of the Niagara's Fury show, which also has good traditional sound and 360 degrees of movie and real water being sprayed on you.
P.S. A peculiar thing happened earlier. I thought I broke a vintage amp from improperly running set B speakers into a secondary amp's RCA input while set A were running 16 ohm speakers, terrible idea in so many ways. It worked for a while and suddenly clicked off randomly when at no volume. I turned of the B speakers and it would not click back on, you know that delayed click all the vintage amps have that comes about one second after switching the main power on. Well, a few hours later I clicked it on and bam, it works. But the output is backwards! Left and right switched. When you turn the balance knob it's the opposite way, and I never touched the connections, they're proper.
P.S. A peculiar thing happened earlier. I thought I broke a vintage amp from improperly running set B speakers into a secondary amp's RCA input while set A were running 16 ohm speakers, terrible idea in so many ways. It worked for a while and suddenly clicked off randomly when at no volume. I turned of the B speakers and it would not click back on, you know that delayed click all the vintage amps have that comes about one second after switching the main power on. Well, a few hours later I clicked it on and bam, it works. But the output is backwards! Left and right switched. When you turn the balance knob it's the opposite way, and I never touched the connections, they're proper.
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you're correct - according to the article there were four pieces H&J which connect to panel "D" to elevate the enclosure. Seems to me the recessed hole could be replaced with just a hole in the enclosure's "top" then elevate the drover with a mdf ring to gain clearance so the cone can't ever hit the throat plate. There's only so much that could be done in this volume - sealed box, bandpass boxes, tapped horn, B4-B6 reflex, elfzilla - it is intriguing :^)
But the South African's box was the smallest size there was, and who knows if he just made it by making it 5/9 the size (18>10 inch driver) of what Graham Holliman specified, he seemed to be incapable of posting the original Gragam Holliman document which he claimed he had and could scan, which is suspicious. The size suggested by another user on AVforum suggested it to be much larger than the South African's, and the South African's instructions for the 12 and 15 inch box seem to be simply proportional to the increase in driver size, which makes no sense since box tuning is not dependent on this..... Why can't someone just have the specs on G.H. original 15 or 18 inch design, whichever it was...
This is from the Original Document of the patent and looks like the one. There are many other illustrations there to add to the confusion as well as to detract from my reliability on the truth of this matter.
All sizes | Graham Holliman Velocity | Flickr - Photo Sharing!
All sizes | Graham Holliman Velocity | Flickr - Photo Sharing!
i've gone over Gragam Holliman's designs and he is simply designing an electronic Jug. just a really big one.
example: Jugs - The Jug Band Cookbook - The Corner Jug Store
This has some low notes coming from a jug... huh... http://juneberry78s.com/sounds/j14029-04.mp3
example: Jugs - The Jug Band Cookbook - The Corner Jug Store
This has some low notes coming from a jug... huh... http://juneberry78s.com/sounds/j14029-04.mp3
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Thank you for finding this stuff.
Well, this looks a little more understandable and easier to build, so why aren't these popular?
PS not such a great "wiki" if I have to pay for it.
Also, I don't get it, the tube to the right looks like it passes all the way through with no openings, the one on the left simple goes half way through. What's the purpose of item 13 except that it holds the tubes in place? It looks like just a big ported box with an extendable port and a dummy woofer. What the heck. If by "Helmholtz resonator" he means "big box with low tuning frequency" I guess he succeded. He also calls it "portable."
The fact that it just so happens to be a simple cube is also suspicious. And to end it all right in the beginning of the description it says "a plywood box." Come on, in 2003, you're using plywood? I made one box out of plywood, and that was only because it might have had to sustain some moisture.
Well, this looks a little more understandable and easier to build, so why aren't these popular?
PS not such a great "wiki" if I have to pay for it.
Also, I don't get it, the tube to the right looks like it passes all the way through with no openings, the one on the left simple goes half way through. What's the purpose of item 13 except that it holds the tubes in place? It looks like just a big ported box with an extendable port and a dummy woofer. What the heck. If by "Helmholtz resonator" he means "big box with low tuning frequency" I guess he succeded. He also calls it "portable."
The fact that it just so happens to be a simple cube is also suspicious. And to end it all right in the beginning of the description it says "a plywood box." Come on, in 2003, you're using plywood? I made one box out of plywood, and that was only because it might have had to sustain some moisture.
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Because most listeners are not interested in johnny one note high Q resonant boom boxes that work so low.
Well I am, but after reading the description, all it really is a large box with a low tuning frequency. It really is just that. How can this guy have gotten a patent and why would he pay for it? The only unique thing is the adjustable ports for different frequencies. Okay, this is your "Jonny 1 note high Q" box, but the Graham Holliman seems to be a legitimate LF generator.
He doesn't even say how to wire the speakers, anything about phase, and even says that "some cancellation is to be expected"?!?! Hello, no. Cancellation shouldn't occur until below the tuning/helmholtz frequency. From what I understand, all that happens when you try to tune a box too low is that the port becomes to resistive and it just acts like a sealed box. However, this box is huge which appropriates such a low tuning, as the ports are not that long realtive to their six inch diameter. Heck, I built an 8 cubic foot irregular cubic box and think it looks silly, and this is over three times the volume, bringing me back to my earlier point that it might as well just be a sealed box that you get inside of to "experience the wave" as the air pressure is radically oscilated. Anyone ever taken dB measurements inside a sealed enclosure?
Once agian, though, I do like to point out, we see the same principle that a low excursion woofer must be used and at low power, letting the box do the work.
He doesn't even say how to wire the speakers, anything about phase, and even says that "some cancellation is to be expected"?!?! Hello, no. Cancellation shouldn't occur until below the tuning/helmholtz frequency. From what I understand, all that happens when you try to tune a box too low is that the port becomes to resistive and it just acts like a sealed box. However, this box is huge which appropriates such a low tuning, as the ports are not that long realtive to their six inch diameter. Heck, I built an 8 cubic foot irregular cubic box and think it looks silly, and this is over three times the volume, bringing me back to my earlier point that it might as well just be a sealed box that you get inside of to "experience the wave" as the air pressure is radically oscilated. Anyone ever taken dB measurements inside a sealed enclosure?
Once agian, though, I do like to point out, we see the same principle that a low excursion woofer must be used and at low power, letting the box do the work.
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The flickr image I posted a few posts back is the one, then? Because I was confused by all the sketches. And you're not denying that it works, then, and that it does cover over three octaves as it claims?
Graham Holliman Velocity | Flickr - Photo Sharing!
I'm just not getting the bottom picture, why the rabbit ear attachment shaped thing? Is that the bottom side of the top piece where the driver is mounted? It certainly can't be the area under the woofer. Is the dotted line part the part that has to be chamfered at 45 degrees? Or is that just the entrance to the bath tub part X? And does it explain anywhere how pronounced the bowtie shaped outcropping (is it even an outcropping?) into the box the part represented by the dotted lines is? In the profile cutaway view it should be shown crossing the gap where the driver fires through hole Y. The bowtie shaped part looks exactly like a UHF clip on to a small TV's rabbit ears I had once. Essentially, the only part that is confusing me now are the specifics of the bowtie part. Other than that it looks pretty simple. The amount of sound you get blowing over the top of a very large jug is incredible considering the minimal power and efficiency of your breath, so it stands to reason that this should be very efficient.
Graham Holliman Velocity | Flickr - Photo Sharing!
I'm just not getting the bottom picture, why the rabbit ear attachment shaped thing? Is that the bottom side of the top piece where the driver is mounted? It certainly can't be the area under the woofer. Is the dotted line part the part that has to be chamfered at 45 degrees? Or is that just the entrance to the bath tub part X? And does it explain anywhere how pronounced the bowtie shaped outcropping (is it even an outcropping?) into the box the part represented by the dotted lines is? In the profile cutaway view it should be shown crossing the gap where the driver fires through hole Y. The bowtie shaped part looks exactly like a UHF clip on to a small TV's rabbit ears I had once. Essentially, the only part that is confusing me now are the specifics of the bowtie part. Other than that it looks pretty simple. The amount of sound you get blowing over the top of a very large jug is incredible considering the minimal power and efficiency of your breath, so it stands to reason that this should be very efficient.
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3 octives... not a chance, it covers 6-15hz. That's 1.3 octives.
The x shaped thing is a support/spacer for the top which is sitting on the lower box.
The drawings suck.
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